Method of fixing bristles into ferrules of brush heads

ABSTRACT

A method of fixing bristles into ferrules of brush heads, comprises providing a composition comprising an epoxy resin, applying the composition to end portions of the bristles, locating the end portions of a bunch of the bristles within a ferrule with the resin in contact with the ferrule, and effecting curing of the resin to adhere the bristles to the ferrule. The resin composition is such that the curing is effected in no more than 60 minutes and the resin on curing adheres within and to the ferrule and does not undergo excessive shrinkage during curing or subsequent cooling such that its adhesion to the bristles and the ferrule is not lost.  
     Further, a method of fixing bristles into a ferrule of a brush head, comprises providing a composition comprising an epoxy resin and including a curing agent based upon a fatty acid and an aliphatic amine, the method comprising applying the composition to end portions of the bristles, locating the end portions of a bunch of the bristles in a ferrule with the resin in contact with the ferrule, and effecting curing of the resin to adhere the bristles within and to the ferrule.

[0001] The present invention relates to the manufacture of brushes andin particular to the fixing of bristles into ferrules of brush heads.

[0002] It is known to fix bristles into ferrules of brush heads by useof polyurethane resin systems, polyester resin systems and epoxy resincompositions comprising a Mannich base.

[0003] Such known methods are all attended by disadvantages.

[0004] Polyurethane resin systems have hitherto provided far too costly.Polyester resin systems give excessive shrinkage and thus the adhesionof the bristles to the ferrule fails.

[0005] With use of known epoxy resin systems, comprising a Mannich base,post operations cannot be carried out for at least four hours, which isthe time the resin takes to cure at an acceptable temperature, and it isnecessary to rely on the weight and viscosity of the resin to penetrateand wet out the bristles to ensure that the bristles are adhered withinthe cured resin.

[0006] The present invention aims to provide an improved method offixing bristles into ferrules of brush heads.

[0007] There has now been discovered an epoxy resin composition whichwill adhere to bristles and ferrules and can be cured in an acceptablyshort period of time and will not shrink and loose its adhesion to theferrules on cooling.

[0008] In accordance with a broad aspect of the invention there isprovided a method of fixing bristles into ferrules of brush heads,comprising providing a composition comprising an epoxy resin, applyingthe composition to end portions of the bristles, locating the endportions of a bunch of the bristles within a ferrule with the resin incontact with the ferrule, and effecting curing of the resin to adherethe bristles to the ferrule, the resin composition being such that thecuring is effected in no more than 60 minutes, preferably no more than30 minutes, and the resin on curing adheres within and to the ferruleand does not undergo excessive shrinkage during curing or subsequentcooling such that its adhesion to the bristles and the ferrule is notlost.

[0009] In accordance with a further aspect of the invention there isprovided a method of fixing bristles into a ferrule of a brush head,comprising providing a composition comprising an epoxy resin and acuring agent based upon a fatty acid and an aliphatic amine, such as analiphatic triamine, the method comprising applying the composition toend portions of the bristles, locating the end portions of a bunch ofthe bristles in a ferrule with the resin in contact with the ferrule,and effecting curing of the resin to adhere the bristles within and tothe ferrule.

[0010] The exceptional bonding property of the epoxy resin compositionincorporating the curing agent is a function of the polarity of theamide group derived from reaction of the fatty acid and the aliphaticamine. Specifically, the carbonyl component of the amide group bringsabout a particularly strong withdrawal of electrons, thus enhancing thepossibility of forming polar bonds.

[0011] It will be appreciated that the curing agent, based upon a fattyacid and an aliphatic triamine, is a modified epoxy curing agent. Asuitable commercially available curing agent is that available under thetrade name EX 1080 from Acene Limited of Bradley Hall Trading Estate,Standish, near Wigan, Lancashire, WN6 0XQ, England.

[0012] Preferably the epoxy resin and the curing agent are mixed in aratio of 3.5:1 to 4.5:1 by weight to formulate the composition for usein the invention.

[0013] The epoxy resin may comprise bis phenol A epichlorohydrin epoxyresin.

[0014] Normally the epoxy resin includes inert filler depending onviscosity required.

[0015] Curing of the epoxy resin may be effected at 50 to 200° C.

[0016] The curing time is typically 30 minutes or less. After curing thebrush head may be subjected to subsequent operations.

[0017] The method of the invention may be used for manufacturing paintbrushes and varnish brushes (e.g. ½ to 7″ in size), paper hangingbrushes, dusting brushes and pegknots, shaving brushes and cosmeticbrushes.

[0018] The brush filling, constituted by the bristles, may be of naturalbristle, animal hair, solid or hollow polyester filaments, solid orhollow nylon filaments, tapered or level polyester filaments, tapered orlevel nylon filaments or a mixture of any of the aforementionedmaterials.

[0019] The invention affords the following advantages.

[0020] Due to the structure of the amide group (formed by reaction ofthe fatty acid and the aliphatic amine) the resin on curing has muchimproved and very strong adhesion to copper, stainless steel and toplated steel (e.g. brass-, tin- or nickel-plated steel), materials ofwhich the ferrule may be made.

[0021] The bonding characteristics of the curing resin allow brush headsto be set (i.e. the bristles to be affixed within the ferrule) at hightemperatures without the resin coming away from the inside of theferrule.

[0022] Fast cure times may be achieved, enabling post operations to becarried out only 15 minutes after curing has been started.

[0023] By processing at elevated temperatures the range of viscosity ofresin can be reduced from 5 to 1 as compared with the use of resinscomprising Mannich bases. This enables cost savings and reduction inlines.

[0024] The resin is stable for up to two hours, i.e. does not start tocure for up to two hours after incorporation of the curing agent, ifstored at a sufficiently low temperature. Below 15° C. is recommended.

[0025] The resin composition has excellent wetting properties and givesreproducible even penetration in brush heads containing natural bristle,animal hair, polyester filament bristles, nylon filament bristles or amixture of such bristles.

[0026] The resin composition may be of such a viscosity at theprocessing temperature that it will penetrate natural bristle of varyingquality.

[0027] The resin improves brush head security without the use ofadditional aids. This is material-saving and labour-saving.

[0028] Initial and ongoing bristle loss is reduced and the brush headshave greater, durability. Brush head shape retention is improved, whichis desirable to the end user.

[0029] The invention is illustrated by the following example.

EXAMPLE

[0030] A resin composition comprising four parts by weight of an epoxyresin comprising bis phenol A epichlorohydrin epoxy resin and inertfiller and one part by weight of curing agent (EX 1080) was prepared.The curing agent had a viscosity of 160 poise at 25° C. The resin had aviscosity of 53 poise at 25° C.

[0031] The resin composition was prepared by mixing the curing agentwith the epoxy resin by pumping through a static mixer at ambienttemperature (21° C.).

[0032] Brush heads were prepared using the resin to adhere bristles intostainless steel ferrules of brush heads, curing being carried out incirculating hot air at 85° C.

[0033] The resin composition penetrated to the edges of the ferrules.The resulting brush heads had cured resin/bristle matrices firmly bondedto the insides of the stainless steel ferrules.

[0034] The curing time was 20 minutes. The brush heads were then readyfor subsequent operations.

1. A method of fixing bristles into a ferrule of a brush head,comprising providing a composition comprising an epoxy resin, applyingthe composition to end portions of the bristles, locating the endportions of a bunch of the bristles within a ferrule with the resin incontact with the ferrule, and effecting curing of the resin to adherethe bristles to the ferrule, the resin composition being such that thecuring is effected in no more than 60 minute and the resin on curingadheres within and to the ferrule and does not undergo excessiveshrinkage during curing or subsequent cooling such that its adhesion tothe bristles and the ferrule is not lost.
 2. A method of fixing bristlesinto a ferrule of a brush head, comprising providing a compositioncomprising an epoxy resin and including a curing agent based upon afatty acid and an aliphatic amine, the method comprising applying thecomposition to end portions of the bristles, locating the end portionsof a bunch of the bristles in a ferrule with the resin in contact withthe ferrule, and effecting curing of the resin to adhere the bristleswithin and to the ferrule.
 3. A method according to claim 2 , whereinthe epoxy resin and the curing agent are mixed in a ratio of 3.5:1 to4.5:1 by weight to formulate the composition.
 4. A method according toany preceding claim, wherein the epoxy resin comprises bis phenol Aepichlorohydrin epoxy resin.
 5. A method according to any precedingclaim, wherein the epoxy resin includes inert filler.
 6. A methodaccording to any preceding claim, wherein curing of the epoxy resin iseffected at 50 to 200° C.
 7. A method according to any preceding claim,wherein after curing the brush head is subjected to subsequentoperations.
 8. A method according to either preceding claim, wherein thecuring is effected in a no more than 30 minutes.
 9. A method of fixingbristles into a ferrule of a brush head, substantially as describedherein in the Example.